Method for forming an image

A method for forming an image, comprising the steps of:

• charging a surface of a latent image bearing member;
• forming an electrostatic latent image on the charged surface of the latent image bearing member;
• developing the electrostatic latent image with a nonmagnetic one-component toner by a developing unit to form a toner image;
• transferring the toner image to a transfer material with or without passing through an intermediate transfer body;
• and
• fixing the toner image on the transfer material, wherein
• the developing unit comprises:
• a toner container for accommodating the nonmagnetic one-component toner;
• a rotatable toner bearing member in a cylindrical shape for bearing the nonmagnetic one-component toner and transporting the toner to the latent image bearing member, which is provided in contact with the latent image bearing member;
• a toner-supplying member for supplying the nonmagnetic one-component toner accommodated in the toner container to the toner bearing member, which is brought into contact with the surface of the toner bearing member at a position upstream of a contact position between the toner bearing member and the latent image bearing and is constructed of a rotatable elastic body in a cylindrical shape with a rotation axis in parallel to the rotation axis of the toner bearing member;
• and
• a toner regulating member for regulating the amount of the nonmagnetic one-component toner on the toner bearing member, which is brought into contact the toner bearing member through the nonmagnetic one-component toner,
• the following relational expression (1) is satisfied when the diameter of the toner bearing member is represented as Rd (mm) and the diameter of the toner-supplying member is represented as Rs (mm):
• 1≦Rs−Rd≦10 (1),
• the nonmagnetic one-component toner comprises a toner particles comprising a binder resin, a colorant, and a releasing agent, and an external additive,
• the addition amount of the external additive is 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the toner particle,
• the external additive comprises a silica fine particle treated with a silicon oil, and
• the nonmagnetic one-component toner has a degree of aggregation of 5 to 30% and an electric resistivity of 1×1014 to 1×1018 Ω·cm at an electric field of 1×104 V/cm.